Jim, add to your list, a good professional education.
I understand Dave's "area' gurantee, He will make it a point to not sell his stuff to another guy in your area, giving preferential treatment to the first buyer in each area. I guess the technical question is what defines an "area"?
If Dave hits apon an previously untapped segment, it would potentially be worth many times the money to most, as I don't see anyone out there doing anything special right now, in fact I see quite a few spending more than they should of ho hum advertising.
I'm going to guess, whether we hear rave reviews, or condeming criticism with Daves's plan, It will boil down to are you willing to work it, or is it gonna sit on the shelf like the other stuff people bought in the past?
I'm familiar with the average cleaner and the average guys marketing efforts.